Slowly stream in the olive oil with the food processor on, until it is emulsified and well combined.
1/3 cup olive oil
Store in an air tight container, in the fridge.
Notes
To use for marinade - pour 1/2 the vinaigrette into a sealable plastic bag. Add 1 pound chicken, and let sit in the fridge for 1-2 hours. Grill chicken. Brush remaining vinaigrette over the chicken to serve. Adapted from Epicurious